Two victims of a knife attack at London Bridge have died, police have confirmed.
Metropolitan Police commissioner Cressida Dick confirmed on Friday evening that three more victims are currently being treated in hospital for their injuries.
A device strapped to the suspect was a hoax, the head of UK counter-terrorism policing said.
He is believed to have been wearing an electronic tag and had recently been released from prison for terrorist offences, The Times reported.
Met Police earlier said that a man had been detained. It was not immediately clear whether this was the same person who had been shot.
A security source told PA news agency that the man had been known to police and had links to terror groups.
The incident started in Fishmonger’s Hall, an events space at the northern end of the Bridge, with the suspect apprehended on the bridge itself just moments later.
Dick said officers were working at “full tilt” to understand what had happened, as well as determine who the suspect was and whether anybody else was involved.
Prime minister Boris Johnson chaired a Cobra meeting on Friday night, before which he described the events as “heartbreaking” and said he had “long argued that it is a mistake to allow serious and violent criminals to come out of prison early.”
The bridge was immediately evacuated and shut both ways in the aftermath of the incident, while Borough Market on the south of the river was cleared and a cordon set up. A large cordon remains in place on Friday evening.
Both the Met Police and London Ambulance Service declared a major incident, with a huge emergency services presence remaining on the scene.
London Bridge was evacuated, however reopened later on Friday evening with some services delayed or cancelled as scheduled returned to normal.
Scores of people were seen running down St Thomas’ Street as the incident unfolded.
A video from the scene shows what appears to be police pulling equipment out of a vehicle nearby.
Those in the video can be heard saying: “They’ve actually got guns out. They’ve got the guns out.”
HuffPost UK saw police escorting people in Fishmongers Company uniforms out of a building, one “covered in” what was believed to be in someone else’s blood.
A staff member from the company told us he had seen an attacker with a “big knife” and that someone inside the building had been injured.
Unverified footage – apparently taken just outside the building – shows officers grappling with someone, and a man in a suit emerging moments later holding what appears to be a blade.
It is not yet clear where the incident started. An area stretching from London Bridge to Cannon Street is now cordoned off.
BBC footage from the scene shows officers and sniffer dogs investigating a large white lorry parked across three lanes of the road.
BBC correspondent John McManus told BBC News that he had heard several gunshots on London Bridge.
“There appeared to be a fight going on on the other side of the bridge, with several men attacking one man,” he said.
“Police then quickly arrived, including armed police, and then a number of shots were fired at this man.”
The bridge has been cleared by police, “but there are more shots going on”, McManus added.
Staff working for News UK, whose offices are by London Bridge station, reported being held in their building as police dealt with the incident.
Prime minister Boris Johnson said “anybody involved in this crime and these attacks will be hunted down and will be brought to justice” as he paid tribute to the “bravery” of the emergency services and members of the public who intervened in the attack, stating that the UK would “never be cowed or divided or intimidated by this sort of attack and our British values will prevail”.
The PM added that there was a “certain amount that the police are able to share with us at the moment” but that it was “not yet entirely clear and they are not at a stage where it is possible to go public”.
He also said meetings were ongoing within Number 10, stating that “to the best of our knowledge the incident has been contained”, and confirmed he would be reviewing whether or not election campaigning would continue as normal in the wake of the attack.
Labour leader Jeremy Corbyn said: “Shocking reports from London Bridge. My thoughts are with those caught up in the incident. Thank you to the police and emergency services who are responding.”
He also later confirmed that the party was suspending all general election campaigning for the evening as a “mark of respect for those who suffered” in the attack.
“We must remain united across all our communities, and we cannot let our democratic process be derailed by acts of terror,” he said.
“We are suspending campaigning in London tonight as a mark of respect for those who suffered in this attack. We will not be cowed by those who threaten us. We must and we will stand together to reject hatred and division.”
Meanwhile, London mayor Sadiq Khan said: “Thank you to our brave emergency services who responded to today’s horrific attack. Every day they put their lives on the line for us – running towards danger in order to keep London safe.”
Neil Basu, the head of UK counter-terrorism policing, said: “At approximately 2pm today, police were called to a stabbing at a premises near London Bridge.
“Emergency services attended including officers from the City of London Police and Metropolitan Police.
“A male suspect was shot by specialist armed officers from City of London police and I can confirm that this suspect died at the scene.”
Speaking to reporters later on Friday, Dick added: “The empty ideology of terror offers nothing but hatred and today I urge everyone to reject that. Ours is a great city because we embrace each other’s differences.
“We must emerge stronger still from this tragedy. In doing that we will ensure that the few who seek to divide us will never, ever succeed.”
On Friday evening the University of Cambridge said it was “gravely concerned” by reports of the incident, with students, staff members and alumni believed to be at a conference in Fishmonger’s Hall.
A spokesperson wrote that the university was “urgently seeking clarification and further details” about the incident.